Why Is Nest Thermostat Blinking? (Red, Green, Orange)

You installed your first Google Nest thermostat for your HVAC system and since the installation, you’ve noticed that color lights are flashing from time to time.  You now wonder what the purpose of the lights is and what you should do when a specific color light is blinking.   

The color lights on your Nest thermostat give you specific messages when they are blinking. A red blinking light, for instance, tells you that the battery is low, while a green blinking light informs you that the thermostat is updating.  Usually, you don’t have to take action when the lights are flashing, unless one of them keeps on blinking longer than usual.  

In this article, I’ll explain the purpose of each light and indicate what action steps might sometimes be needed to rectify the issue.

Google Nest thermostat blinking

Summary of the different lights on Nest

Although there are many models of Google Nest thermostats, the different blinking lights on the thermostats carry the same messages and indicate the same issues in all the models. (The European version of Nest also has a yellow light.) 

The lights on the Nest thermostat, and the reasons they are blinking are as follows: 

  • Blinking red light – The thermostat battery is low.
  • Blinking green light – The thermostat is updating the software, starting up, or restarting.
  • Blinking orange light – The thermostat battery has to be charged.
  • Blinking white light – The thermostat is reconnecting with the router.
  • Blinking blue light – The blue light is usually blinking when you start up your Nest thermostat. It should stop after a minute or so. 
  • No light is blinking but you have a blank screen – Different reasons, including that the battery might be completely depleted.   

Let’s now look at each blinking light on your Nest thermostat in more detail. 

Detail regarding the blinking lights

Blinking red light

When the red light is flashing on your Nest thermostat, it is not a warning about a crucial problem that needs immediate attention. The red light is just indicating that the thermostat battery is becoming low and that you should attend to the issue as soon as you can – everything is still working.

However, if you haven’t checked your thermostat recently, the red light might be flashing already for quite a while and the battery might now be very low. If this is the case, you might have a blank thermostat screen as well. 

All you can do is wait. The red light will stop flashing when the battery reaches its full charge again and the screen will then also turn on again. It takes some time for the battery to recharge – it can take up to an hour. 

If it seems as if the battery is not charging, locate the USB port on the thermostat and connect a UBS cable directly to the device. It should be either a mini or micro USB and not a computer USB cable or unpowered USB. This will ensure that the battery gets charged. 

Blinking orange light

When the orange light on the Nest thermostat is flashing, it indicates that the thermostat has to be charged with a USB cable. This may occasionally happen when the “normal” charging process has not been sufficient.  

To fix this issue, just follow these easy steps:

Step 1: Remove the thermostat display from the base.

Step 2: Find a USB cable that can charge the device. It should be either a mini or micro USB, depending on your thermostat’s specifications, and not a computer USB cable or unpowered USB.

Step 3: Connect the USB to the port in the thermostat.

Step 4: The screen will start up when the thermostat starts to charge. You will get a message on the screen that you must connect the display to the base again. 

Step 5: After you’ve placed it on the base, carefully push on the display until you hear a click sound. 

Blinking green light

Your Nest thermostat sends you a message if the green light is flashing. The thermostat is informing you that it is updating or installing software or restarting. The light will only keep on flashing for a minute or two. Thus, you have nothing to worry about when the green light is flashing.

However, when the green light is not flashing but just stays on, it is an indication that the thermostat has frozen while the updating was in progress. 

To resolve this issue take the following steps:

  1. Carefully take the thermostat screen off the base and then put it back into position. When you are putting it back, ensure that all the pin connectors are correctly and accurately aligned. If everything is aligned, you should hear a click sound when the screen snaps back into position. 
  2. If your thermostat is still frozen, push down on the display for about 10 seconds and then release it. This should fix the problem. 
  3. If the thermostat is still not working, consult your owner’s manual, or check online for further steps to take to restart a frozen thermostat.

Blinking white light

When the white light blinks on the thermostat, it means that the thermostat is reconnecting with the router. This may happen after you’ve done a manual restart or a software update, or when the thermostat is reconnecting with the router.

To get the thermostat back on, take the following two steps:

  • Ensure that all wires are properly fitted with the connectors.
  • Ensure that the thermostat properly fits on the base.

If the white light is still blinking, turn off the thermostat by pressing on its ring. Then you can set up the thermostat again.

Blinking blue light

Getting a blinking blue light on your Nest thermostat is rather common. It usually happens when you start up your thermostat, and it should stop after a minute or two. 

If it doesn’t stop blinking, take the following steps to fix the issue manually:

  • Step 1: Ensure that the cooling and heating wires are connected correctly.
  • Step 2: Ensure that the thermostat wires aren’t sticking out. 
  • Step 3: Take off the display of your thermostat and carefully put it back again. Ensure that the pins align properly. 
  • Step 4: Press the thermostat ring for about 10 seconds. The display will go blank.
  • Step 5: Set up your thermostat.

Blinking green and orange lights

Sometimes you get orange and green lights simultaneously. To rectify this, take the following steps: 

  1. Take the thermostat display from its base.
  2. Connect a USB cable to the thermostat and charge the thermostat for 2 to 3 hours. You have to use either a mini or macro USB, depending on the Nest thermostat model you have. 
  3. Carefully place the display back on the base.
  4. Start the Google Nest App, go to “Setting,” then to “Technical Info,” and then to “Power.” Your Nest thermostat should work smoothly if the thermostat is fully charged.

No lights are on, but you have a blank screen

There are various reasons why the screen can go blank while no lights are blinking. The most common reason for this is that the battery might be discharged completely. Fortunately, this can easily be fixed by recharging the thermostat with a UBS cable.

Let’s look at some other actions you can take to resolve this issue if the USB connection hasn’t worked. Ensure that 

  • the display is properly connected to the base,
  • the thermostat’s power button is set to “On,”
  • the Nest thermostat is connected to all the devices it works with,
  • the wiring within the thermostat is connected and not damaged, and that 
  • the fuse is not damaged.

Check to see if your thermostat is functioning and if the screen is still blank; it is recommended that you contact an HVAC technician. 

Blinking yellow light

The European version of the Nest thermostat also has a yellow light. When it blinks, it is an indication that the connection between the heat sink and the Nest thermostat is broken. The U.S. version does not have the yellow light – we just mention it here for interesting sake.


The lights on your Nest thermostat are, in principle, there to communicate with you. They tell you with what process the thermostat is busy, and in most instances, you don’t have to take any action. However, if the blinking continues for longer than normal, there are certain actions you can take to resolve the issue.

Charles John

Experienced HVAC technician with 8 years of experience in the industry. Capable of handling all sorts of heating and cooling equipment as well as proficient in operational management, construction-related techniques such as preventative maintenance, electrical troubleshooting and AutoCAD

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